Videophone systems are known in the telecommunications industry. With the recent development of new compression techniques over standard telephone lines, it has now become possible to effectively transmit and receive video images over a standard telephone line. Many technological developments have contributed to the development of this growing industry. For example, improvements in communication standards have increased transmission rates to the order of 56 Kbps to 64 Kbps. Other developments in imaging equipment have also contributed to the development of video telephones, such as the development of single-chip CMOS image sensors by OmniVision Technologies of Sunnyvale, Calif., the assignee of the present invention.
With the newly developed technology, many video telephones have been proposed by combining a video image capturing device, a standard video display unit, and the appropriate circuitry to provide video and audio communication between two like devices over a standard telephone line. Examples of several video telephone designs are described in U.S. Pat. No. 4,953,196 to Ishikawa et al. (the “Ishikawa patent”) and U.S. Pat. No. 5,191,601 to Ida et al. (the “Ida patent”). These references disclose commonly known video telephones and several developments related to enhancing image quality and camera mounting features.
One fundamental problem with traditional videophones is that they require a user to remain in one physical location while using the video and audio capabilities of the videophone. For example, if a user wants to make a phone call, the user has to remain in the viewing area of the video camera and at a distance that allows them to view the video display. In typical home video phones, as shown in the Ida patent, the video camera is affixed to the base device. In other special designs, such as the phone disclosed in the Ida patent, certain video phones have a flexible video camera mount, one that allows a user to change the direction of the camera's viewing area. However, even when a video phone has a camera capable of viewing multiple viewing directions, the operator of the video phone may be unable to move away from the base unit without moving out of the camera's viewing area. Moreover, this system may not operate for users who would like to transmit images from multiple viewing areas, such as transmitting images from multiple rooms in a building.
In addition, as shown in the above-described examples, traditional videophones typically include a telephone part having telephone functions, a line control circuit coupled to a public analog telephone line and other audio communication devices, such as a speaker and microphone. These built in features add cost to the development and manufacturing of each device and, further, do not provide the flexibility for an operator to use their existing telephone with the videophone unit.